title: Effect of ventilation technique and airway diameter on bronchial lumen to pulmonary artery diameter ratios in clinically normal beagle dogs.
abstract: In dogs, a mean broncho-arterial ratio of 1.45 ± 0.21 has been previously defined as normal. These values were obtained in dogs under general inhalational anesthesia using a single breath-hold technique. The purpose of the study was to determine whether ventilation technique and bronchial diameter have an effect on broncho-arterial ratios. Four healthy Beagle dogs were scanned twice, each time with positive-pressure inspiration and end expiration. For each ventilation technique, broncho-arterial ratios were grouped into those obtained from small or large bronchi using the median diameter of the bronchi as the cutoff value. Mean broncho-arterial ratios obtained using positive-pressure inspiration (1.24 ± 0.23) were statistically greater than those obtained at end expiration (1.11 ± 0.20) P = 0.005. There was a strong positive correlation between bronchial diameter and broncho-arterial ratios for both ventilation techniques (positive-pressure inspiration rs = .786, P < 0.0005 and end expiration rs = .709, P < 0.0005). Mean broncho-arterial ratio for the large bronchi obtained applying positive-pressure inspiration was 1.39 cm ± 0.20 and during end expiration was 1.22 cm ± 0.20. Mean broncho-arterial ratio for the small bronchi obtained during positive-pressure inspiration was 1.08 cm ± 0.13 and during end expiration was 1.01 cm ± 0.13. There was a statistically significant difference between these groups (F = 248.60, P = 0.005). Findings indicated that reference values obtained using positive-pressure inspiration or from the larger bronchi may not be applicable to dogs scanned during end expiration or to the smaller bronchi.
authors.affiliation: Division of Diagnostic Imaging, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
authors.forename: Mariano
authors.initials: M
authors.lastname: Makara
authors.forename: Matthias
authors.initials: M
authors.lastname: Dennler
authors.forename: Manuela
authors.initials: M
authors.lastname: Schnyder
authors.forename: Rima
authors.initials: R
authors.lastname: Bektas
authors.forename: Patrick
authors.initials: P
authors.lastname: Kircher
authors.forename: Evelyn
authors.initials: E
authors.lastname: Hall
authors.forename: Tony
authors.initials: T
authors.lastname: Glaus
mesh_terms: D000818:Animals; D001980:Bronchi / Q000033:anatomy & histology*; D004285:Dogs / Q000033:anatomy & histology* / Q000502:physiology*; D005260:Female; D008297:Male; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000033:anatomy & histology*; D012123:Pulmonary Ventilation; D012119:Respiration; D014057:Tomography, X-Ray Computed / Q000662:veterinary; D014132:Trachea / Q000033:anatomy & histology*
keywords: broncho-arterial ratio; computed tomography; expiration; inspiration; ventilation technique